Ritalin side effects.

I have been on ritalin medication for ADD for a couple of months now.
I started on 20mg per day and have recently had my dose increased in the last couple of weeks.

I am definitely feeling the benefits of the medication - better concentration, not lost in my own thoughts as much, etc.

But I have been having potentially quite a serious side effect: extreme mood swings.
One moment I could feel really relaxed, calm and chilled out about everything, but give it four hours or so and I might feel almost suicidal.

Does anybody have any experience with ritalin?

Thanks in advance.

I've been on ritalin for 4 years (64mg) so yeah quite a lot. The side effects I had were, firstly the whole reduced appetite (I lost 20lbs) but you soon get used to it and it doesn't make much difference any more. The mood swing thing, sometimes it can make me feel really low. I don't know why but it can make me feel a bit depressed so this might be normal but ask me if you have any other qns

I don't feel depressed as such, like I'm not crying constantly, I just feel that don't belong here, as though I might feel more comfortable being a part of the Earth again. Just as I was before I was conceived. One of nature's mistakes maybe?
I've failed in life haven't I?