Hi, I Am Experiencing A Strange Condition For The Past

Hi, I am experiencing a strange condition for the past 10 years but can't say what is this ailment. Usually I wake up fresh in the morning but after morning bowel movement I feel sleepy and tired with foggy and sluggish mind. Then I had to take half to 1 hr rest or sleep and this symptom vanishes but only for some hours and after 3~4 hrs I again experience this sleepy and brain fatigue condition especially intensify after lunch and again I have to take a nap/rest of approx 1 hr. If I avoid eating my symptoms become less.
So I have to take these intermediate rests 3~4 times a day from the past 10 years. I consulted many doctors from gastroenterologist, psychiatrists, neurologists and homeopathic but no cure. Some say it is IBS, some say it is Chronic Fatigue Syndrome, some say it is depression, panic attack etc. They tried a lot of medicines from tricyclic, tetracyclic antidepressants, SSRI, IBS medicines and much more. I had undergone numerous tests from complete blood picture, thyroid test, blood sugar and pressure tests, EEG to colonoscopy but nothing come unusual in tests.
What u think, am i suffering from? any guess about my illness which may help me.