It sounds like you're having issues with your thyroid. Even if your doctor tested you for hypothyroidism, and the results came back negative, that still doesn't mean that you don't have a problem. If you haven't been tested, see if you can convince your doctor to run some tests.
The best natural remedies for thyroid issues are:
1. Liver Flush
every three to four weeks for about 6 months to a year. Liver congestion can cause thyroid issues.
2. Use an enema to take care of constipation when necessary. Try to stay away from drugs.
3. Go gluten free and stay gluten free.
4. Make sure you get to bed before 10PM every night, and make sure you get up around 6AM every morning.
5. Eat your largest meal of the day at noon.
6. Eat very light at night.
7. Stay away from large legumes (kidney beans, etc) and stick with smaller ones (lentils, mung beans,etc).
8. Use Himalayan Salt.
9. Take kelp supplements daily and possibly supplement with iodine.
Also, if you haven't had a thyroid test, see if you can convince a doctor to give you one.
One more thing ... when you say you're eating a healthy diet, what are you eating?