Shortness of breath at the gym today?

i took pre workout today and went to the gym and I've only recently started taking it i have and anxiety and depression starting on meds tomoz i was doing weights was ok then second excerise half way through i put them down cause it felt like i couldn't breath i got to the gym all the time its a first time this has happened and i felt like i couldn't and was going to faint what could be cause?