Why do I have a white pus blister on the back of my throat?

Ok, well I do not have tonsils, they were removed like 4 yrs ago. I have been sick for 5 weeks almost now. It started out with a dry hacking cough..I thought it was my dust mite allergy...well I got bronchitis and coughing up mucus, sinus drainage ..blah blah. Ok then I took Keflex 500 mg for a week. Felt great for 3 days TOPS! Then I wake up again... with a sore throat! So right now I have no other symptoms than a severe sore throat when I swallow, fever on and off, headache, a white pus blister on the very back of my throat. I been gargling hot salt water, tylenol for fever and ugh! do i have strep throat?? bc i have no tonsils..... and im not coughing!!! any answers? professional answers? is penicillin needed?