Since 1 mnth i am doing 10 min elliptical & 20 mins treadmill workput daily.my periods used to b timely, now its late by a day.is workout stressful?

Relationship - not!: ably do. really doubt that there's a relationship. The exercise amounts you describe are very moderate and sound like a good thing as long as you do them correctly and if you've not had pain in joints or muscles - you probably do. The possibility of your thyroid condition being involved is greater, but also not much. If you're concerned, have an exam. Best!