Hello Adam,
Having read your case it seems like your MCL cannot be the only structure involved in your trauma.
The MCL is firmily attached to the medialmeniscus and usually this fibro-cartilagineous structure tends to get torn too if the MCL is involved (infact also the ACL tends to get affected, in a typical clinical manifestation called "the unhappy triad")
It sounds very weird they didn'tMRI your knee and I would suggest to have this investigation done.
Football 5 a side, even if played in a "non competitive way" it is not indicated on people recovering from such knee injuries as it is highly demanding on your knees and ankles.
Regards
Emanuele