It sounds like an allergic reaction to me, but could be something else. I would definitely see the doctor. If it is an allergic reaction of something that touched your mouth, you don't want to chance it spreading to your throat next time. Other conditions however may cause this, so it would be best to see a doctor.
Have you ever had a cold sore? If not you could be experiencing a cold sore which can be brought on by stress. Cold sores are usually painful blisters on the skin of the lips, mouth, gums, or lip area. They are caused by herpes simplex virus and usually go away in 1-2 weeks. I would suggest going to a doctor for some antiviral pills(acyclovir) since your symptoms are recurring. Remove any stress from your life as well.
Sounds like you have what I have. It's actually mainly from dehydration or too much sodium(salt) intake. I would suggest using Chapstick: Lip Moisturizer (it's in the blue tube) almost constantly and drinking about 8 glasses of water a day. My lips were the opposite though. They split and cracked on the outside but itched and swelled on the inside. It may seem like a pain but the chapstick really help- and I do mean specifically that one. Mine got so bad that neosporin, abreva, blistex, carmax, even bagbalm did nothing for it. I tried everything and that's all that works if I let it get bad. I talked to my dr about it and he's the one that told me that it's dehydration and my higher salt intake (I have unhealthily low sodium levels so I can't cut back on salt). Just remember to drink more water all the time.
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In all probability you have very dry lips. A lip balm preferably petroleum jelly, Vit B supplements, iron, and honey should help. If it does not please consult a skin specialist.
There is one very simple thing that I would like to tell you. Lip area when it heals, forms a scab like dry layer. This layer though looks bad should be left as such so that the skin underneath it can get time to grow and cover the lips. If you peel this dry skin, the healing process starts all over again with dry skin on your lip.
Dehydration is the commonest cause of dry cracked lips. Drink plenty of water and see.
The other possibility is iron and Vit B deficiency. Along with multivitamin B (not a multivitamin which also has other vitamins) take an iron preparation and see.
They can also be caused by allergies and infections. You could either be suffering from contact dermatitis or from allergy to some food. You should get an allergy test done, either a skin test or RAST, to know what you are allergic to. Contact dermatitis could be due to tooth pastes, mouth cleansers, spoons, cups, glasses, food items, cosmetics, shampoos, etc, basically anything that comes in contact with your lips.
Another possibility is eczema. Herpes infection is another possibility if there is a history of kissing or sexual contact (can get aggravated in presence of vitamin deficiencies, dry cracked lips, infections etc). Also get your blood sugar checked both fasting and two hour after food to know what if you have diabetes. Hypothyroidism too can cause this type of skin and lip problem. I would suggest you consult a skin specialist regarding this. Take care!