I've Had Throat Issues For About Three Weeks Now. One

I've had throat issues for about three weeks now. One tonsil is quite swollen and the other has white patches on it (this sometimes clears a little after gargling with bicarbonate of soda but it comes back) it is a little sore but it's not excruciatingly painful. My glands are also swollen but they have been swollen for a while, I seem to suffer from viral illnesses often. Ive had 10 days of penicillin v which did not do anything. I've had a test for glandular fever and a throat swab which have come back negative. My doctor said it must be viral but I'm unsure because of the white patches on my tonsil, I'm really concerned about the length of time this has been going on. I should also mention I've been suffering from thrush on my tounge for a while now due to antibiotics, I've been unable to shift this I'm wondering if this has something to do with it?