It sounds to me like you might have an infection. The pain between feeds can be thrush, but recent research has shown that it is more often an infection. A course of antibiotics might be an idea to see if the pain goes away. Of course antibiotics will make you more prone to thrush too, so some probiotics as well could be a good idea.
I hope something works for you soon - even though you are doing so well at putting up with the pain, it would be much better not to have it!!
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