Ugh, Here's what you do!!!!
1. Dose Flatworm exit, and prepare to do a water change (This is only nessasary if you have alot)
2. Take suction pump and as you see all those worms floating, suck them up off the rock and into a bucket doing this you should get just about all of them, Then fill your tank back up with ro.
3. If you problem still seems to be there do it again, Trust me if you do it right the first time it will go away. Flatworms are no the end of the world, THEY ARE EASY TO GET RID OF! I wish i would get them just to show how easy they are to get rid of....IF you have AEFW well then your f'ed lol
FWE will not hurt your tank or anything just remember if you have a lot just do a water change and siphon them out after. Do this and you will be fw free, and then you can move on to more productive things.....
If you really can't figure that out shoot me a pm, I will personally come eliminate your tank of fw but you must buy fwe....