IUI/ Clomid and now 6dpo spotting/blood

Lise
Hello. We had our first IUI last Wed April 27. Second time taking Clomid. 
I took it a few months back without IuI. We thought we got lucky and got preggo that time, I spotted about 10dpo and my cycle was 34 days... But not - Dr says Clomid can make you "spot" midcyle and also make your cycle long.
Problem now. 
IuI last Wednesday. Today is 6dpo and just has seen spotting red blood like the start of a period... Just a little with a wipe and done. Nothing more just like before.  I still have over a week until AF and they won't do a blood test until 17dpo. 
Has this happened to anyone before? Spotting with Clomid midcyle ?? I don't want to get excited like I did the previous time bc I was heartbroken and this time we invested so much more. Thanks.