What Causes Blood In Split While Suffering From Sore Throat?

hi yes i have sore throat thats red and very painful to swallow i also have some blood in mucus when i spit it out. swallowing pain eases up a little while after i eat something. i also have a very dry mouth. no fever, no white patches, no chills or body aches. i did take some amoxicillan (500mg twice a day) a few weeks ago and after 3 days it felt much better. i ended the antibiotics a few days after and then the pain came back about 4 days later after the 8 days on amoxicillan. i do have systemic lupus. im a 44 year old male. thank you