What Are The Symptoms Of Seborrheic Dermatitis?

Hi Doc, Im 22 and got eczema a year ago, yes i have asthma but i never had eczema before. Its started on my arm now under my knees and now on my face. Im really worried and i have done a lot of research and i think it is seborrheic dermatitis but then again some of the symptoms of atopic dematitis seem to be showing. I have tries a lot of things like tea tree oil which get rid of the dryness but my skin becomes more red. I think its bacteria related because the time it came about i wasnt sleeping in the best conditions to be honest and also when i steam my face it all goes clear i dont understand.. Help DOC THANKS