worried 2 positive 1 negative

i have been feeling sick the last week and a half and been getting bad headaches.. i brought 2 test from sainsburys yesterday... 1 was invalid and the other was negative... i woke up this morning and went to throw them in the bin until i released one said positive i googled and released it could be a evopartion line so i went to the chemist today and brought 2 of them and both came back positive but  a very faint positive line i didn't believe them and was in shock so i brought 2 from saisnburys and now the sainsburys one has  come back negative im worried now... 5 days before af trying to conceive for 2 years and never seen a positive before