I have had a iud inserted for 20 years I have not had a period for 3 months I feel bloated and a bit sick

It'll take time for your period to come back because you had your iud in for so long but that feeling of bloatedness and sickness is probably just your body sorting its self out and getting ready for your period. Your periods when they do come might be irregular also but if your worried that you are pregnant go and get a hpt or go to your doctors for ablood test