Hi, I have a question: My period is 7 days late, I usually have a very regular 28 days cycle. We had sex on my most fertile days and since then I have been feeling extremely tired, naseous, had lower abdominal cramping and hot flushes. I took 2 pregnancy tests, one on day 4 & one on day 5 and they were both negative. I've just noticed some light pink spotting. Could this be implantation bleeding or is it my period starting late? I'm still getting slight cramps. Is it too soon to take another test? Any advice will be gratefully received. Thanks.

It could be from a pregnancy, or from an off cycle. You could certainly try another test, or you could see your doctor about having a blood test. Some women don't get a positive result on a urine test for a few weeks or so.
If negative... wait until your period is due next month and see what happens (you might just be skipping a month) or see your doctor before that time.