Help.. Im so unsure please can someone help me identify these symptoms…?

i am a 15 and 1/2 years old
and for about 2 weeks i have had everything aching and a pain which feels like someone has stabbed me in my mid – right back occurring about 2x a day. then this week i have been feeling pretty drowsy and tired. To top this all off i found a lump on my higher arm which has grown about 5mm which as you can imagine, this scared the life out of me! dunno weather these are connected. but either way i really need some help and advice on what to do.. anything i have no clue im so scared!!! help me please!! im just sitting here, out of my mind scared not knowing what to do!