I have yellow patches on my throat and soreness only on one side.i tested negative for strep and mono.it clears up every few days and comes back ?

Do you have any: other symptoms? If you're tired and/or have fever, you may need a more specific mono test, depending on which one you had(should have EBV titers). If that's been done already, you should see an Ear, Nose & Throat specialist who can further evaluate this for you.

Viral: Although these test are negative they only rule out the most common problems that one sees. They do not rule out other viral illnesses or infection that might cause the same symptoms. Please note that this can be lasting one to two week as well. If it has gone on for some time you need to see an ENT.