Hi Peterspots. I'm so sorry to hear that you are going through this. I have had similar problems which have sadly got worse in this peri nightmare. I can tell you what helped me; for the urethral pain, drink a glass of water (or squash if you prefer) with a teaspoon of bicarbonate of soda. This neutralises the urine and stops it from stinging the irritated urethra. For the bladder spasms, get some Buscopan tablets, which are for IBS but basically relieve muscle spasms. Take two tablets three times a day for one day only. This is what my GP advised me to do and it works. If you've had the cystoscopy and your bladder/urethra are fine, it is just all irritated probably and you need to allow it to calm down.
Please let us know how you get on.