Why are my swollen and painfull?

i have the implant contreception so it isnt pregnancy i dont have periods so it not because im due to start i have just started goin to the gym last 3wks goin 4times a wk feeling really bloated and heavy my legs seem swollen too as well, i lost bout 2 lb in the 3wks of exercise and eatin healthy if any one has any idea why my s have swelled so much