Hi I Am 44 Years Old And For Quite A

Hi I am 44 years old and for quite a while I have had problems with feeling a little light headed, concentration issues, fatigue, memory, that are off and on. Some days i feel brilliant and sharp others tired and my speech slurred a little, feels like I have to much saliva. Just recently my eyesight has got somewhat worse too. I have had blood tests for diabetes and no probs. I only suffer from a cholesterol and take cholesterol medication as well as an aspirine daily. the doctor has stated my testosterone is low, but I am not sure this is the main factor. can you help.