It is not possible with 1 test to have both positive and negative. It is possible, but NOT likely, to get a false positive or false negative on a test.
Yes. Both are quite possible.
There are a few possible explanations. The most likely is that you contracted chlamydia within those three months. Another possibility is that you got the first test so soon after infection that it could not yet be detected. A false negative or false positive test is another possible explanation.
Certain kidney and liver diseases will cause a false positive. Also possible triggers for a false positive are diabetes, Amoxicillin, or tonic water.
No; having a false positive test result once you are not more likely to have it again.
If your blood test came back positive then it is positive.
False positives are possible.
Yes, it is possible to get a false positive. There are certain medications that can cause you to test positive for THC, mainly antiretroviral medication, even though there is no actual THC present in your body. It is also possible for a urine drug screen to be faulty and give a false positive, however this is unlikely. They will then re-test the same urine with a new test to determine if this was indeed the cause of a false positive.
A false positive pregnancy test is extremely rare, so I would say no, if the tests read positive you are most likely pregnant.