Had cold 3 weeks ago & earache. gp prescribed paracetamol & ibuprofen for pain, ciproxin hc ear drops & amoxicillin. still ear blocked with some pain?

Ear effusion: Is possible after an ear infection to have persistent inflammatory fluid which blocks the ear ongoing and I think this is likely. Not urgent but a GP assessment with tympanometry testing can be helpful in confirming this. Usually with time will resolve although some persist so worth GP check for this possibility as a minority that persist may need ENT referral. See GP and all the best.

Otitis externa: Sounds like the GP was treating an infection in the ear canal rather than behind the drum. These infections can be stubborn and take time to improve. Keeping the ear dry as much as possible will help, e.g. using a hair dryer into the ear after showering +/- ear plugs in the shower. May need repeat exam +/- ear swab to identify particular types of infection (fungus, resistant bacteria).