i acutally have the same problem in my 25G righ tnow, here's the typical procedure i'd follow through with ich:
a) do a 20% water change first, syphon up all the crap stuck in yoru gravel
B) put back with fresh dechlorinated water
c) add the proper amount of aqarium salt (be careful if you have any scaleses fish like bottom feeders and stuff)
d) turn up the temperature to 80-82F
e) add in some ick medicine
Keep doing that everyday for 5 days and the ich will probably be gone. If you see it getting worse you might want to try and isolate the female bettas as they can be kept in litlte coantiners (just like males) becase they breathe on the surface.
The higher temperature will cuase the ick to speed up their cycle faster, and hopefully teh salt and medicine will be enough to kill them. I guess i would be a little careful with changing the water everyday becuase some fish are more sensitive to water hcanges than others. You dont' want to further stres shtem out becuase that'll give the ick a chance to strike again.

good luck, i'm still hoping my tank will pull through

p.s. do you mind me asking what fish you have in your 10G?