I suffer in my right heel too and have found correct shoes helps me a lot. The Clarke’s Unstructured have been brilliant and I live in them. Not pretty but very comfy. Their summer sandals are good too.
If I wear anything else for a day it hurts like mad. Have to be careful with boots and when running.
I work in foot care product design and development
Ideally you need orthotic insoles, lots of anti inflammatory drugs and to relieve the acute pain get a really cold can of coke and stretch your arch over it regularly by rolling it backwards and forwards under your foot
If you haven’t already you need to see a podiatrist not just a GP!