Reversible or irreversible pulpitis

Question

So, long story short, I went to brunch on Saturday and bit on something hard in my breakfast burrito. I think it was an undercooked bean because it broke into a few pieces after I bit it. Anyway, on Monday I got a throbbing pain in my gums that would come and go and it continued through today, but moved to the tooth that I was worried about from my burrito incident. Btw, it's my second molar on the top left of my mouth. So, not the wisdom tooth, not the one in front of that, but the one in front of that.

No abnormal sensitivity to cold. If I drink cold water, I can feel it but then it goes away as soon as I swallow. No pressure with biting or anything like that. The pain DOES radiate to my cheekbone and to my ear on my left side. It's like a really really dull ache that's there for most of the time. And some pressure.

I went to the dentist yesterday and he did all these tests. He tapped on it with a metal tool, nothing. Well, there was one spot where I was like, I can "feel" it, but it doesn't hurt. No "pain." He did the freeze test with dry ice on a cotton ball, for the most part nothing but when he touched one spot, I was like "yup, I can definitely feel that." When he took the ice away though, the pain immediately subsides. He told me that the spot he touched is where my gum is receding a little bit. He said it was an area of a bit of exposed root and that's the only space on my mouth that I jumped. He also did a bite test where I bit on this stick in different positions and nothing, no pain. He also did an X-ray and didn't see anything there.

So, he said it could be reversible or irreversible pulpitis. He also said it could be my sinuses since my sinus hits right where that tooth is. Only issue is that I don't have a sinus infection. At least I don't think. I have a bit of blood in the nostril in the morning, but that's it.

I went to eat last night and was completely fine. Hard pizza crust and all. And cold drink. When I brush my teeth, just the gum feels irritated but the tooth doesn't bother me.  I notice that when I move my head quickly or move it down and then back, I can feel a slight rise in pressure in the area where the tooth is. Also, my gum is very irritated there. I feel like the gum is actually painful and not the tooth.

Any advice? Any indication of how long it takes pulpitis to either heal itself or get worse and I'll need a root canal? The dr said he didn't see a cavity or any cracks in my teeth.

 My dentist said that it's basically a "watch and wait." He thinks I will be fine but said if it gets worse, I should see an endodontist.