I had it happen about two weeks ago. Tested, got my 3+, had one left in the pack so thought I'd test again the next day. Then got 2-3. Totally freaked out, phoned the doctors, they did bloods and my levels came back fine. Tested again two days later and got my 3+ back. I honestly wouldn't panic too much just yet, although I know how hard it is. Keeping my fx crossed for you!