If 20mg of ritalin ir 3x a day didn't help me, can concerta (my only other choice I guess) help me? Why would another methylphenidate med help?

ADHD. Concerta is the extended release version of Ritalin or methylphenidate. It is usually better than taking a short acting drug several times a day. Most likely it needs to be adjusted to your needs. Other amphetamine drugs are vyvanse (lisdexamfetamine) or the short acting adderall. Strattera and Intuniv are effective non amphetamine drugs. When treating adhd is important to rule out other medical problems.
Possibly. Why is your only choice methylphenadate? There are other medications that may help if Ritalin does not. There may be other formulations of methylphenidate that would help. Discuss this with your doctor.