Okay so I wrote a whole paragraph for you after what you just showed. But had to remove it all, as I was wrong. But I will tell you initially what I thought after reading your post my diagnosis was allergic dermatitis or herpes simplex/zoster.
But it was not making sense, so I searched the net as the symptoms you are describing are nowhere described in the books, and it took only sometime after searching the net, that symptoms you are describing what I am pretty sure now is the correct diagnosis is cholinergic urticaria. I will provide some literature for you to read.
Medscape: Medscape Access
Cholinergic urticaria. DermNet NZ
http://www.rarediseases.org/rare-disease-information/rare-diseases/byID/249/printFullReport
For treatment go to a good dermatologist (the drugs I am naming in the bracket is the brand name) they will give you anti-allergic like, cetirizine(zyrtec, zanlan, baydal, ocitra) or Loratadine(histanil, loragix). If these drugs do not help then you will have to be shifted to montelukast(myteka, montiget, singulair) or ketotifen(zatofen). Also do not forget to read in those articles the portion that tells how to prevent this.
But be sure to see a good dermatologist and do not start treatment yourself. No blood test will help if you still want to get some tests done then go to lab and say do a "CBC with differential count" and an "IgE level". Other tests described in articles are rare to find in pakistan.