Sinusitis after pool water splashed inside my nose

5 days ago we swam in the pool (it’s my pool) and a bunch of water went into my nose. Monday morning, after blowing my nose in the morning I developed the worst nasal pain/soreness/burning in my life. Lasted almost a day and got. Better at night. Tuesday just a head pressure and on Wednesday I developed body aches (pretty severe lasting all day). I gave up and took one pill of Augmentin. Felt somehow better with body aches but pain persisted on Thursday and today Friday it’s pretty bad.
Maybe too early to tell but I felt like Augmentin only helped with body aches. Pain is there, now getting worse.

Again, I don’t know if it’s true sinusitis (have no viral infection) or terrible sinus irritation/inflammation.

Having severe side effects of Augmentin and I was wondering if it’s needed.

Btw. I know my sinuses have drained issue (did couple of cscans) but this came right after pool water exposure. My pool is vey well maintained.

Any insights? Especially should I take antibiotics?