My baby's father after 6 month and then took my iud off and a month later got pregnant I'm kind of worried that the baby could not be his is it possible that the baby could belong to some one else just because I had an iud

I doubt that the child is another mans but if you really want to know go in for a DNA test

Your post is difficult to make sense of. The subject line is not really where the question is supposed to begin. What's the time line you're talking about here? When was it that you had sex with this other man and how long after was it that you had sex with the second man? Depending on how far apart the encounters were, a dna test may be the only way to determine who the father is. But I'm not sure where your comment about 6 months fits into this.

Not quite sure how your question reads!! are you saying you split from your baby's father, then had sex with another man but then got back with your baby's father after 6 months apart,had sex, which lead to pregnancy a month later?
If this is the case, when was your last period within the 6 months apart from your baby's father? If you had regular periods right up to the time when your baby father returned(after 6 months)then the baby has to be his which is why you are now pregnant a month later by him!!

My apologies if I have read this question completely wrong!!