Is this evaporation line please help

I have been getting alot of cramping and feeling sick my period was the 4th July but it was brown and alot lighter then usual lasted only 4 days. I didn't think much to it untill I've been feeling sick so I asked my partner to bring me some pregnancy tests home on the night after work. I was so excited it took a test on the night time and that was neg. I didn't think I could be pregnant, but was wanting to be so bad so I took again the next morning I waited around many a min and saw was neg and was upset so just chucked it on the sode and left them in my room the next day I went to throw them away and noticed it has a line is it just an evap line can any one help. Thankyou