What are these spots on my negatives?

I noticed spots like the ones in the upper left on some of my home developed color negatives.

This roll was one in a Paterson plastic tank, using the twister to agitate every 15 seconds.
Is this from bubbles in the developer? Almost seems like a hair got stuck in there and bubbles formed along it.

I had a problem that looked similar to that and it ended up being an air bubble on the film. It was the only time, since I started developing my own film, where I had that problem. It also happens to be coincidental with the fact that it happened when I was using the twister on a Patterson tank to agitate my film. I quit using the twister to agitate my film and I never had that problem again.

So, yes, my guess is that an air bubble caused those marks and the reason why they seem to zigzag and skip is because, each time you turned the twister, it caused the bubble to move a tiny bit.

The main lesson I learned was to be extra conscientious about tapping the tank on the table after every agitation cycle.

One reason why I started getting slack about tapping the tank was because I was worried that I would crack the plastic tank by hitting it too hard. I solved that problem by cutting a small, 12-inch square piece from an old, rubber floor mat to keep handy for tapping my tank on. You could use an old mouse pad or anything like that.

IF you bang the tank on the table a couple of times after filling it then use the twister only for the first agitation then thereafter for the rest of the development time use inverse agitation with the tank lid firmly on it will avoid air bells.

looks more like a watermark to me -- try re-rinsing and drying, using photo-flo. No squeegie. Make sure there's enuf foto flow in the water so the film hangs with a smooth sheet of water on the film when you hang it, no open areas.