Pain in back upper molar...is it serious?

• I have been getting constant dull pain in my very back upper molar for about 3 days (started tuesday). It always starts around mid-afternoon and goes until mid-to-late evening...I feel no pain during the night. Applying pressure with my finger I do feel increased pressure (not pain) during the painful periods. It hurts to chew hard things during the painful periods. I do not feel pain while applying pressure to the tooth during non-pain periods but I do feel a little increased pressure. However, I do not feel the same kind of pressure when I touch my other back molar. I do not feel any pain/pressure while applying pressure to my jaw or gum line with my finger. Flossing and brushing do not cause additional pain/discomfort.

• There is no sharp pain. I would describe it as mildly annoying, definitely something I can work through without pain medications. its more dull and constant for a couple of hours during the day and then goes away during the night/morning.

• The pain sometimes extends from my tooth into the left nostril (e.g. through my sinuses?). I am not experiencing any cold or flu like symptoms. I do not have any discharge from my nose beyond what is normal for me (e.g. I do not have a runny nose). It does not hurt to palpate my nose or sinus areas.

• I was getting periodic headaches last week which is unusual for me - I typically only get headaches when I am dehydrated. However, I have had no headaches in the last two days, so last weeks headaches are probably coincidental.

• I brush and floss daily (I swear!). I have not seen a dentist in a while and I do not have a regular dentist.

• I had my wisdom teeth removed at 17, and I'm now 26.

So my question is should I see the dentist ASAP or can this wait until next week as I have a final on Saturday? Thanks!