I was playing soccer 3 days ago and about 2 minutes into the practice my knee began to keep me from running. when i got home it was swelled a lot ?

Knee: i would ice it elevate it and take some ibuprofen but check it out with an orthopedist

Knee swelling: Sounds like an acute injury. Rest Ice Compression (Ace wrap or brace) and Elevation along with an antiinflammatory like Motrin, should help, but you do need to see a Doctor for further evaluation

Possible: Strain or sprain. Rest, immobilize, elevate, ice and use analgesics. Get evaluated