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I had a similar pain although mine started earlier, I had my physio work at it, but the relief only lasted a couple of hours, it was my ribs pulling appart

Unfortuately for me it didn't repair it self until after DD was born, but once she was born it was instant relief

I rubbed it, used heatpacks, anything "natural", but the pain itself it is really quite distracting as well, so it can be hard to concentrate at times.

You could perhaps try a physio or chiro and see if they can give you any ideas.