Breast pain when sleeping on side?

I posted this in the breastfeeding group a while ago but didn't get much response. I'm breastfeeding and ever since my son was born I can't sleep on my sides without terrible breast pain, which gets bad after about 10-15 minutes of lying on my side. Once I switch to lying on my back the pain fades in about a minute. It's not clogged ducts, I'm totally clueless. And I hate it because I miss sleeping on my sides, I'm totally uncomfortable sleeping on my back which is what I've had to do the past 4 months. I know I should ultimately talk to a doctor, but for now...any ideas or advice?? 😩