how do I tell the difference?

So.... when I check my strings they are up high and sort of wrapped around my cervix. I can feel then with my fingers but how can I tell if my iud is dislodged? Would it hurt in my cervix? And would I be able to feel a distinct difference between the string and iud? Like it feels thick but that's all I feel I can't like pull the string to lengthen it to feel it so I am a little confused as to what I should look out to feel. Also every single time I check my strings all I do is barely touch them and feel my cervix and every time after I get BAD BAD cramps. Is that normal??