PSA can fluctuate due to prostate cancer, but not usually by that amount. That might suggest some other cause for at least some of the PSA, but doesn't rule out prostate cancer as being partially responsible.
Some other things which can raise PSA would be urinary tract infection, prostatitis, physical disturbance (digital rectal exam, anal sex, bicycle/horse riding, etc).
7.6 is still a level which should cause referral for further investigation. The next step in the UK would be a digital rectal exam, a mpMRI scan, and sometimes a flexible cystoscopy.
Why did you have your PSA measured in the first place?