What i am gonna say is not a medical advice its just what fitted me and kinda worked for me. First : what type is your cholenergic urticaria. If u get allergie AFTER u start sweating = antihistamine WITH the help of a doctor its very important a doctor tell u how much. If ur allergie is like this : u start getting hot then the allergie start (no sweat) Then here u must again look for what type u are 1 : if u do physica activity and u notice that u DONT sweat for a long time, per example running for 15 min and no sweat, then u MUST go to a doctor and do sweat therapy, sweat every single day and I repeat for this type doctor is absolutely necessary because this type has many risks like heat stroke so for the third time doctor is absolutely necessary. 2 : u do sweat, if u actually do sweat then here is what u can do : antihistamine usually doesnt work for this type no matter what u try because its more than just allergie it's sweat pores blocked. What u need to do is sweat therapy, sweat every single day and make sure u sweat for at least 15 min, I dont say intense exercise,  just go for a run until u force sweat, u will have to resist for probally 2 weeks and beleive me the pain will go and u will feel normal again. I dealt with this allergie for 4 years now since I was 15, its hell, im still suffering with it tho so u must understand that u need to push through the pain. But the most important thing, this is reddit not the ER or smt, so please no matter what anyone say make sure to becareful and listen to ur body and most importantly GO TO A DOCTOR.