Peanut butter is highly allergic to lot of people but u have fever too, so another reason may be denge, typhoid?
So avoid sunlight.
Locally apply caladryl lotion 3 part with one part of BETNOVATE N mix them properly after taking a bath. U can apply it even in evening too.
Tab montek lc one at night.
If intensity decrease well n good. N note it mind not to use peanut in any form.
If yet persist u can go for blood work
CBC
CRP
Denge NS1 WITH ANTIBODIES.
WIDAL TEST.
TAKE PLENTY OF LIQUID N WATER
LIGHT DIET SEMILIQUID KHICHADI PORRIDGE RICE CURD RICE DAL POHA UPMA IDALI WITH WHITE CHATANI.
FRUITS ANY AVOID MANGO.
BANANA PAPAYA, WATERMELON, ETC.