Is it Fermenting?

Hey Guys, I did my third all grain batch a few days ago, making an American IPA.
Now When I received my shipment ( 2 batches, Aprox March 25) I did not refrigerate the liquid yeast.
I had made up the first batch an April 2 (Irish Red Ale)(Also at this time I put the yeast for my IPA in the refrigerator) Everything went well, it bubbled. So on April 11 I started my second batch (IPA) I took out the yeast Aprox 4 hours prior to pitching.
After putting it into my 5 Gallon glass fermenter the rubber stopper had slipped through, I then fashioned a stopper out of duct tape, positioning the airlock atop to what seems to be airtight. Now 5 days after (April 16) there is no bubble action, however I see white foam on top of the beer.
So what do you guys think? is it fermenting?

Thanks in advance

White foam sounds like krausen, which means it's working.

Ignore the airlock. It's a bad indicator for fermentation. You probably don't have the airtight seal that you think you do (which is perfectly fine). If you see krausen, you're fine.

If you're really unsure, take a gravity reading. That's the best way to tell.