Thanks for the query.
Do you have any discomfort or pain during sex ?
Usually causes for lack of interest in sex could be due to pain or discomfort while having sex, lack of intimacy with husband, tension and emotional stress with causes tiredness
and fatigue. Also some hormonal
disorders like PCOD, PMS can cause lack of interest. This needs to be investigated of you feel unusually tired, gained weight recently, feeling of bloating of stomach, swelling of feet and development of any hair on chin.
Also psychiatric conditions like mood disorders, depression
etc. can cause loss of interest in sex. This needs to be diagnosed by a leading Psychiatrist
Eat a diet with plenty of proteins and fresh fruits and green leafy vegetables. Drink 1-2 litres of water daily. Get 6-8 hours of sleep daily. Do Yoga for stress relief. Do daily brisk walking for 40 minutes a day. Avoid smoking, alcohol and caffeine.
Consult your Doctor to find any medical causes for this problem but before that make sure you have proper diet and get proper sleep. Get a consult with your Psychiatrist to rule out mood disorders.
Wishing good health.