Hello,
Your symptoms are suggestive of photodermatitis or Polymorphous light eruption (PMLE) .Avoidance of sunlight is the main treatment. Stay inside during the brightest hours of the day, from noon to 3 p.m and wear long sleeves, slacks, and a wide-brimmed hat whenever harsh exposure is probable.Also wear sunscreen (at least factor 30) with a high UVA protection level when in sun or even indoors.
Regarding your problem of dandruff, eat a healthy diet. You can also take vit B6 and vit A and E which are good for hair and skin. Try medicated shampoos for dandruff. There are a number of over-the-counter shampoos available that can help. The most effective ingredients -- antimicrobials -- to look for are zinc pyridinethione, selenium sulfide, sulfur and ketoconazole (also available by prescription). If your hair is colored, don't use products with selenium sulfide or sulfur.
If the symptoms persist then pls consult a trichologist and get yourself evaluated for hormonal imbalance or fungal infection with P. ovale.
Hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional queries.
Put Urticaria into your search Engine, we call it Hives here, there is a lot of information there also pictures so you can compare, if it is Urticaria it is often something you are allergic to, they give you anti histimines for the itch but that doesnt get rid of it, very often it has to run its course, unless you can figure out what triggered it, sometimes differant foods and Shower gels, and Laundry washing liquids. check it out and good Luck aslo change your shampoo