Here goes.......... I have an iud fitted. I had sex with a one night stand on the 9th December. About two weeks later my boobs started to hurt. Ive felt a little sick but not too much. I really dont want to be pregnant, im 42 and a single parent. I bought two clear blue pregnancy tests this morning and did one. The test came up negative. Hurray i thought so i put it in the bin. Checked it again just now and its now got the line down the middle which says im pregnant. Ive done the second test and that says im not pregnant. HELP!!! Do the tests alter hours after you have done them??