Severe pain in left breast

I'm 32+4. Yesterday afternoon I noticed my breasts, particulalry my left breast, had started to feel tender again. I didn't think much of it, as the tenderness in early pregnancy tended to be in one and then the other. Well, I woke up at 1:30 in the worst pain I've ever experienced. It felt like someone was sticking a knitting needle down my nipple! 
After some paracetamol and warm compresses I was able to get to sleep,though it's still pretty tender this morning. I suspect it's a blocked milk duct, but if anyone has experience with this please let me know.