At what point should I be concerned its something other than sleep regression?

My son started waking up every hour throughout the night about 3 months ago. Now he wont nap. Will not. I got him to nap for 9 minutes today, so that's a win.

At night for the last 4 nights he has been doing this thing were he sits up then starts screaming. I slowly put him back down and this goes on a few minutes then back to the routine of trying to get him to sleep. I haven't had more than 3 hours total a night in going on 3 months. I'm wrecked. And honestly starting to worry. When I talked to his doctor she just said its sleep regression. Does it end?

I feel like this is going to cause horrendous sleeping habits and he starts daycare next week. Pretty sure they are going to hand him right back to me, like, nope.

Anyone else going through this?