When I was reading through your post, Balanitis came to my mind.
Caryopteris gives you some good advice.
The other thing I would mention is yes the steroid creams can cause thinning of the skin if used for long periods of time.
Lotriderm (as I understand) is an antifungal cream. There are different types of antifungal creams available for use on the genitals and there is also a cream that is an antibacterial as well as an antifungal.
As well as the different creams, there is also a single dose oral capsule that is called Fluconazole 150mg. This can be purchase from the pharmacy without a prescription and is a treatment for thrush. You may notice results within 2 days sometimes it can take up to a week. A further dose can be taken after a week if there are no reduction in symptoms.
The only way to confirm whether you do have a fungal or bacterial problem is by having a swab taken at the doctor's surgery and getting it analysed.
Do not use normal soaps or shower gels this aggravates the skin and changes the pH level further aggravating the condition. Use soaps that are skin friendly and also not perfumed. Baby washes may be OK. The doctor can prescribe Dermol 600 which is a macrobial bath emollient for you to put into your bath water. Dermol 400 is a microbial emollient that is used to moisturise the skin as well as a substitute for soap.
If you use condoms, go for the latex free ones. The ordinary ones are likely to aggravate your delicate skin.
Only wear cotton underwear that has been washed in non biological detergents and don't wear any tight clothing.
If you are treated at any time for a fungal problem, your girlfriend also needs to be treated at the same time as bacterial and fungal problems can be passed on from one to the other even when there are no symptoms present.
When you see the dermatologist your condition may be diagnosed as Lichen Planus.
Did the doctor get you checked out to see if you have a glucose intolerance? Having glucose intolerance, or prediabetes can also cause skin problems.
As you also have a skin problem on your scalp, like Caryopteris suggests, use the Nizolral shampoo. It could be that you have a skin disorder, possibly lacking in essential vitamins like Vitamin D, C, E. for healthy skin.
Ask your girlfriend not to wash with soap down below too because you may even be getting an irritation to any residue soaps, shower gels or feminine sprays that she may be using.
As a home remedy, to help to lessen your irritation on your genitals, wash with warm water and gently dry. Then apply lots of natural set yogurt to your genitals and also under the foreskin. You can apply this as many times as is required without having any side effects. It is also effective for use on female genitals too.
Unfortunately, as you have had this problem intermittently for a while, it may be that you will always have to be very careful and manage the condition without actually getting a cure.
Keep to a healthy diet with fresh fruit and veg, and keep your intake of processed foods and sugary foods, fizzy drinks and alcohol to a minimum.
As you know yeast loves sweet.
Best wishes.
Thanks for the reply. Do you reckon the issue is one of a thrush type bacteria / infection then?
No my partner does not have any symptoms. She had thrush once a while back which cleared up as it should with the appropriate meds. We are using condors anyway due to the problems so I don't think there is anything being passed between us.
Treat the penis with Lotrimin cream as directed on the tube for jock itch. Decrease sugar in the diet. Take a probiotic every day. Throw out your socks and underwear and start new, or wash them in hot water with measured Tide and baking soda. Every time. Sheets too.
Does gf have any symptoms of irritation or dryness? Because the female body is much harder to keep free of yeast than the male because it's all inside moisture. Use Nizoral shampoo for scalp alternating with neem shampoo. Use neem soap or tea tree oil soap. Do not use neem around your gf if she might be pregnant as it is bad for fetuses, but it's also bad for bacteria, fungus, and viruses, so it should help you out. Make sure your shower head is clean, not covered in orange slime.
I would continue on the path of what your doctor has advised and see if the situation can be sorted.