Muscle Twitches After Botox in Forehead?

It sounds like you're having some muscle spasms and the muscles treated are trying to work again. Maybe at your next visit with the provider, increase your dose.

    Muscle spasms after Botox indicate that more Botox should be injected into the muscles that have rebounded.

It sounds like you have very active and strong forehead muscles that may need a little extra product to fully relax them. I would return to your physician and discuss this with him/her to either touch up now or inject more product next time. Best of luck! 

It is possible that Botox is wearing off in an area but it is also possible that an untreated area might be trying to work to compensate for the treated area. I do not think that this is a problem because it can probably be fixed with a little touch up. 

If it was "perfect" last week, then I'd assume you have small areas where the Botox is wearing off, hence the twitching. 20 units for the frown lines and mid forehead is a lower dosage, especially for that much area and muscle, so I think you need more units next time.