I do not know what I should do about this?

I think I have either a dissociative (not multiple identity) disorder or PTSD that stems from a very young age. But because of the amnesia (limited to the situation), and the incident being so far back now I'm not sure how to explain it; and I am also afraid that I won't be taken seriously anyone. but it affects my everyday life to a severe degree. I never had any counselling for it (as far as I can remember) but it has always been a problem that I thought was in the background but has been with me my whole life and it was worsening slowly until I recently remembered a good deal about the whole thing and haven't been able to function. what can I do? I've no idea where to startI do not know what I should do about this?
Start with a counselor. If it doesn't feel right, don't stick with him or her. Go to another one. If you can, see a therapist (again, if first or the second doesn't feel right to you, get out and find another). I hope you find someone who can begin to help you easily but it's not always that way. Sometimes it depends on their experience, the chemistry between you and the therapist/counselor/etc. or just how you feel opening up to him or her. If you know someone who sees a therapist s/he likes, start there. You may be in for a long journey with ups and downs along the way but keep at it and it almost always gets better. It helps to understand. You can also browse through the book sections for self-help to get started and learn the language and what they mean by different things. Best of luck. It's better to do these things with some successes and some failures, learning as you go rather than staying stuck and getting worse. It doesn't get better by itself unfortunately.