My handwriting is terrible!?

I'm a lefty and one day I decided to write with my right Hand I practice and practice and I just gave up. So I stuck with my left hand and it's just really ugly I get complaints from teachers thinking that I do it on purpose because I'm lazy etc no! I take my time and it's weird because I can draw very well but can't write well. Why do I write ugly. So yesterday I grabbed a pencil with my right hand and out of no where I was able to write with it! I'm so happy! But why? I didn't practice for months! (writhing style is the same I may write neater with my right hand) very odd