Could be a reaction to PG, could be dehydration.
Not an expert, but just a guess.
I've heard reactions to PG and dehydration are very common problems when people first switch over.
Start by drinking lots of water (lots) and then see if that helps after a day or two.
Then switch to VG if it doesn't.
worse comes to worse take a break from vaping. Your lungs are pretty important :3
I agree ith you ... Cos when I vaped PG I didn't have problems breathing but my chest hurt ... Then switched to PG and I'm fine now ...