Hi, Around March 31 After Blood Work And Breaking Out

Hi,
around March 31 after blood work and breaking out in hives, i was told i had mycoplasma pneumonia. I was prescribed Doxycyline(which didnt work) and now taking certizine(which seems to be working to stop the welts from surfacing, however i turn fire on patches of my skin). I still have about 2wks worth of the second medicine to take. How long before this should pass or should i be taking a stronger medicine? Lastly, should i take tie skin patch test that was recommended? Thanks for your help.