Just restarting to workout, dizzy episodes??

I had the band about 3 years ago and did well for about 1 1/2 years and than we decided to do a revision. I had been working out about 4 days per week for an hour or more and doing quite well and felt good. I also worked with a trainer one day per week. Well, I had my revision done on Nov. 29 to RNY and have had 2 dilatations since. Just can't get out of the full liquid stage. Have been trying pureed/soft, but the pouch isn't quite accepting it yet. Will probably need another dilatation again soon according to the surgeon.

Well anyway. I am aloud to walk, elliptical, and bike. I can lift up to 50 pounds. My core activity restriction has been lifted. I asked if I could resume working with my trainer and taking classes and the doctor said to give it another month until I am doing well at work. I go back to work on Monday and work as a nurse, so it is a physically demanding job. They don't want me over doing it at the gym and then getting sick so I can't work.

Today I started back doing a little bit of kettle bell at home (Used to do this presurgery also). I started with only 5 pound bells, so very light weight. I have a heart monitor watch and my heart rate was right around 140.  After about 15 minutes, I all of a sudden back lightheaded and started thinking I was going to faint. I had enough common sense to sit down quick and checked my heart rate on my watch and it had suddenly dropped to 78.  Has anybody else had this happen? I haven't ever experience this, but it was my first workout besides for walking since surgery.   After I recovered from this episode, I did about 10 minutes of easy core and was fine.  FYI: I was drinking during the short workout and have been getting my fluids in.

I would recommend seeing a doc asap - certain heart conditions could cause this, as well as a lot of other reasons. Better to be safe than sorry.