What Causes Numbness In The Thumb?

Hello I am 18 and i have a pretty intense exercise schedule, today it was a normal day and i went to do squats, i started with a fairly normal amount for me then increased to a larger but still do-able amount then i did quite a bit . I finally finished with a burnout set i did one set of 25 and then felt a slight numbness in my thumb, i thought this was just a pinched nerve, then i increases and did another burnout set, after this set my left thumb was REALLY numb and my right was a little bit numb i felt a little bit dizzy and sat down. After a minute of sitting down my arm went numb about 3/4 up my forearm i almost felt on the edge of "letting myself go" and concentrated pretty hard and took deep breathes. I felt my heart pound in my chest and then slowly i came out of it is 4:53 and this happened at 2 about 2:40 and my thumb is still numb, any advice?