PAIN and poop (ulcer, iron?).....TMI

My most recent labs showed mild anemia, so I have been instructed to double my iron intake and am now taking 120 mg elemental iron (2 of Vitalady's Tender Iron 60mg) a day.  For the past 6 months, I have been taking 1 per day.

After a couple of days at the double dose, my stool turned dark greenish/black, which I knew to expect.  (Sorry...I warned that there TMI here!)  However, yesterday I had to episodes of tarry, sticky black stools, which I *thought* was supposed to be an indication of a GI bleed.  Is that accurate, or is that simply from the increased iron?

Then, last night I had 4 episodes of moderate to severe abdominal pain.  It was stabbing pain, alternating with a dull aching pain.  It came and went from the late evening throughout the night, waking me from a sound sleep 3 times.  There was no cramping, no urge to go to the bathroom....just pain.

This morning, I feel absolutely fine!  No pain at all.  I ate my normal breakfast and feel fine.  Haven't had a BM yet today, so I don't know about that part. 

So......does this sound like the start of an ulcer?  Anything else?  Can I safely just wait and see, or do I need to call my doc right now?  I need to be super careful about days off of work right now, so I would prefer not to go running to the doc if it is not needed, but I also want to prevent a problem from developing. 

I should mention that I also take 20mg of prilosec per day.  I had taken it for 20 years for GERD and then my surgeon automatically puts all patients on it for 3 months after RNY.  However,  I tried twice at 4 months and 5 months, with my surgeon's approval, to stop taking it and each time I have heartburn with in 24 hours.  So, he said to just continue to take it.  Most folks don't have heartburn anymore after surgery, but some do and I am apparently one of them.

Any info would be most appreciated!!  Thanks!