PSA In 2013 Was 2.5; In 2014 Was 3.4; Then,

PSA in 2013 was 2.5; in 2014 was 3.4; then, on 6/5/15 it was 4.3, so my pcp sent me to urologist. Urologist had me take 2 Bactrim per day for 5 days, (from 6/17 to 6/21, inclusive). Took last Bactrim at 11 pm on 6/21, then I went for another PSA at 10 am on 6/22. I just learned today that this came back at 7.2 or 7.3, with free PSA at 30%. We have scheduled biopsy for next week, but I am really scared wondering why PSA would go up 3 points in just 17 days. Anything you can tell me to make me feel even slightly better? I am 71 years old.