KRATON CAN BE VERY DANGEROUS!!!
I have been in your position but researched kratom. There are horror stories of people having terrible stomach pains and having them for 3 days. Do your research before this. As far as the symptoms you have describes. I've felt that too. You need vitamins, amino acids, potassium, and natural relaxants like valerian root. Keva. Melatonin. This will much more beneficial than anything else. You have 90 days clean. Your doing great.
Sub wd's can last quite awhile. All the symptoms you are feeling should go away after a bit. Adding kratom to the mix isnt helping anything. It is interfering with what you are trying to do here and that is get your body and mind cleaned out. I would get off that stuff as quick as you can as you dont need another addiction.
You should be long passed your Suboxone withdrawals. Kratom is not usually addictive and is sometimes actually used during opiate withdrawals in the Far East. However, if abused consistently, it can cause addiction. The withdrawal from it should not be awful or prolonged, though. If you are having issues with insomnia, try using Valerian or melatonin. Good luck to you.