Congrats! 50 squats in my opinion is amazing!
I am thinking of taking that challenge later on in my weight loss. Right now I can only do 5 squats with out injuring myself. Not joking. Once I did 10.... I couldn't walk for 24 hours (Not exaggerating) and for a week I was super sore. 10 was all I could physically do till my legs gave out. I have strong legs-Its the back of my knees and along that area that needs lots of work.