So 4 days ago I fell on my left forearm it was bruised and sore but I could could use it but it's still very sore and swollen still four days later?

See answer. You can try continuing rest and an over the counter anti-inflammatory medication such as ibuprofen, and if still with pain and no resolution than see a dr. As there is always the chance you could have a hairline fracture, etc. Best wishes.