Doctor refuses to send in different doses that are in stock to the pharmacy is that normal?

So there’s a bad shortage in my area and I’m taking 20mg a dosage that has been out of stock for awhile now, I’ve been calling around and everybody is also out. my pharmacist told me they only have the 30mg and I just decided to ask my doctor if they could swap me over and I can cut the pills in half and he said he’d only do the exact dosage, not even less than 20mg, man this is rough 😭