Its like this. 'Doctor, every time I do a pole vault I hurt my back, have you any tablets for it?'   
I'd sung since a toddler but a few years ago got pain in my chin, neck and collarbone. I mentioned this to the ENT specialist (who I was seeing about going deaf) and knowing me to be a singer he immediately presented me with a list of local (Darlington) singing teachers. I had to make the expensive decision whether to go to one OR STOP SINGING. Lots of friends said I couldn't stop could I so there I am.
It's a long long process that has cost me way way more than I make from my few bookings. But I can see the progress, yes the pains have gone but I'm quite hooked on it now I can see how things are building and we come back to things I could not have done and now can.
My teacher analysing what I sing and instructing me what do do is fundamental. A book or online course wouldn't work. You need that expertise.
Good Luck - let me know if any more story might help convince you!
John