No appetite , no sleep, weight loss fast, have energy, no disiness, some shortness of breath, no other pain. what's going on?

Thyroid?: Could be thyroid disease. Could also be due to medications you take or even overdosing on caffeine. I suggest you see a doctor. Good luck and feel better.

Anxiety, sadness,: Depression, anxiety and other conditions, besides medical conditions can be the reason. Good opportunity to get a checkup and a screen for psychiatric disorders if everything comes back normal (examination, labs, whatever your dr considers necessary). Best of luck !

Be seen: There could be many things going on. Be seen for an exam and diagnosis.

Hard to say: These are concerning individually but especially when all together need better evaluation and sooner rather than later. Many different possibilities can cause such things, but you need a good history and exam as a start.