Anxiety disorder

hey everyone im on 10 mg of celexa but moving up to 15mg I just had to leave the gym early because I felt like I was gonna pass out and a I couldnt catch my breathe the gym was hot but ive lifted in hotter weather idk if its the medicine if im dehydrated or what but I just wanted to see what you guya think I should do. im gonna call my doctor and try to get some blood work done but what do you guys think it is?