Yes, my view is based on the facts you do have a case to sue for medical negligence - they failed to diagnose you which has now led to complications.
The NHS Constitution says "you have the right to receive care & treatment that is appropriate to you, meets your needs & reflects your preferences",
If dissatisfied, patients can complain to the NHS - their GP or provider Trust. If dissatisfied with the outcome of the NHS complaint, they can then appeal to the Parliamentary Health & Social Care Ombudsman here: https://www.ombudsman.org.uk/making-complaint
Patients also have the right to compensation where they have been harmed by negligent treatment.
It sounds like they were negligent however you will need a law firm to sue the NHS in a negligence claim - you should be able to avail of a no win no fee agreement meaning nothing to pay up front and you are fully protected from any legal costs if you lose.
The following firms operate in this area :
Patients can also exert pressure by referring the matter to their local Healthwatch - who are patient’s consumer champions - yours can be found here: https://www.healthwatch.co.uk ) / to the local press / to your local MP.
You would also be within your rights to report the doctor to the GMC as a result: 0161(###) ###-####or by emailing *****@******.***