First of all, when you are stressed out, kindly try to find a way out of it rather than indulging in smoking.
And it is appreciable that you are working on giving up this habit.
Causes of Constipation
1. Functional cause- due to decreased gastric motility
2. Irritable bowel syndrome- constipation predominant type.
3. Less consumption of fiber rich foods
4. Less fluid intake
5. Prolonged use of certain medications.
& Metabolic causes, etc.
Though symptomatic relief can be obtained by intake of Laxatives, their regular use is not advised due to the risk of dependance & other unwanted side effects.
However, as long as the underlying cause is not treated, symptoms will keep recurring.
So, kindly consult a Gastroenterologist
& get a proper physical examination done.
Investigations like Ultrasound
scan of abdomen, Colonoscopy
& contrast studies will be helpful to rule out any pathology in the Gastrointestinal tract.
There is no need to worry, you will be fine.
Till then, take healthy nutritious diet rich in vegetables & fruits, exercise regularly and keep away stress.
Wishing a good health.