Pamela, are you short-sighted? Floaters are fairly common, especially if you're short-sighted. I've had mine since I was a kid. One floater in particular is a nuisance, it's big (looks like a ball of sago) and is affected by gravity, so if I'm looking down a microscope, for example, if floats on down to get in the way so I can't tell if I'm looking at what's on the slide, or what's in my eye. Very annoying when trying to sketch what I see... REALLY annoying if it's a blood slide, because this floater looks a lot like a red blood cell at about 300x.
I also have been getting lightning flashes in my peripheral vision for 30 years. At first it came on fairly suddenly was was associated with headaches and a lot of pain, but it settled and nobody could tell me what it was. Since then, the flashes have changed from jagged lightning, to full circles of light. What I think is happening, based on my own observations plus what I've been told by doctors - I am EXTREMELY short-sighted, so the eyeball is much longer. Part of this has meant that with an eyeball not properly round, as my eye looks to the sides the muscles on the outside which are making it move, are pulling in the retinal You see, the orbit, or bone in which the eyeball sits, IS round. At least, rounder than my eyeball.
You get a similar effect if you push on the side of your eyeball, because it distorts the retina which sends an electrical signal via the optic nerve. So in my case - the full circle I now see, is the full circle of even 'pull' on my eyeball (and the retina on the inside) from the muscles moving my eye. My eye doctor knows about it and he keeps a close watch on my retina because there is always the risk that it could suddenly detach after all these years.
Oh, and the lightning flash is white not coloured, because the cells which see colour (cones) are concentrated where they will do the most good, in our central vision. The light-dark receptors (the rods) are scattered round the whole retina and it's almost exclusively rods round to the periphery.
The doctor gave you good advice. Keep monitoring things and ANY sudden change, get it checked out pronto and give them your history.
Marg