Now you've been given good advice so far. The best of which is consult a doctor. I do however have one more to add. Is you juice 100% VG? I noticed that strait VG juice gave me stomach pains so I don't use it. I might be off since I've never heard anybody else say anything like this, it could have been something about the flavor, it could have been the vender, the batch you name it, but that's my experience.
Even if this helps see a doctor or at least be sure to mention it to them on your next visit.
It may not have anything to do with vaping. As suggested before, please see your doctor. We may give you the best advice we can, but we're not doctors.
............ It should't be from not drinking enough water because I normally drink at least 8-10 glasses a day
............ and so if you have some sort of digestive disorder like IBS or Crohn's the symptoms will show up full strength once you quit smoking.
I will chime in here...I have stomach issues since quitting smoking and I HAVE been to the doctor. Let me explain what happens to SOME people when they quit.....
After 1-4 months after quitting smoking some peoples digestive systems will go through nicotine withdrawal. This can cause many symptoms including pains, nausea, bloating, constipation, etc.
It may take several months for your system to get back on track.
Things that help...increased water intake, adding fiber to your diet, taking probiotics.
Vaping does not allow the nicotine to absorb as deep into your body as smoking does so even tho you are getting nicotine from vaping your system may still show signs of withdrawal.
Most people assume it is from vaping because most of us start vaping at the same time that we quit smoking and symptoms appear. Also vaping is new to your system so naturally you would assume new symptoms are from the new vaping.
After all of that....this may not be your problem so please see your doc if symptoms continue. I am not a doctor...just passing on personal knowledge.