Heat Rash - Allergy to Aloe Vera

Past summer, i got a sunburn and put aloe vera on in large quantities and i got a horrible constant heat rash, barely much of a rash just more like slightly red goose pumps just where i had put the aloe. I hadn't been allergic to aloe vera before. a month later i accidentally used a shampoo with aloe vera, confirming i was allergic because i had an almost immediate itching reaction.

Now 5 months later i've been getting a horrible heat rash, the prickly sensation all over. i need to be in a cold place or it gets bad. and i've been avoiding aloe vera. Its been going on for 2 months like this. But i finally found out a drink i have has a very small quantity of aloe vera in it. so i found the culprit, but i have been drinking this for years. Just as i've used aloe in other things before to.

So my question is, why have i become allergic to aloe vera. some people i have asked said there is something non natural in my body that is reacting with it? The past 2 years have been horrible for me medically, including lyme disease and a bad case of mono. So could one of the medicines i took have effected me like that. If you need more info i'll be happy to share more. But this has basically ruined my life for the past 2 months.

Thank you