Suggest Remedy For Hair Fall

Hi,

Hopefully you could help me. I am a 19 yr old female and I had recently dyed my hair for the first time about 2 weeks ago from a box dye kit. Lately my hair is coming out a LOT on a day to day basis. I am always finding long strands on my shirt and shoulders. When griping my hair (dry) at the nape of my neck then sliding my hand down to the bottom, I am left holding about 10 strands, which happens almost everytime I do it, after a couple of hours from doing it last. I had cleaned out my hair brush a few days ago and after I brushed my hair about 6 strokes, the brush was somewhat filled with long strands again. Before dying my hair I would only find about 2 or 3 strands on a clean brush. When washing my hair I get the same results at I do when my hair is dry, Although maybe 15-20 strands come out instead of 10. Also my scalp is a little sore to the touch and it feels like it does when I keep it tightly up for too long, however my hair has not been up tight in a while. Its just very un-normal because my hair always used to be very healthy and strong. I never used to have this much coming out. Other than my hair falling out I am in very good health. Is there any other reason other than the hair dye as to what is causing this problem? Or is there even a problem at all? Thank You.