Seeking expert counseling is a sign of strength. A personal relationship with a caring professional is proven clinically effective.
I believe that I can help.
Does she give any other reason than she is "too tired"?
That is not a credible reason.
She has lost interest in you, or is suffering from depression, or has some other problem that needs to be addressed.
You never did say why you lost all of that weight.
This is a festering problem for both of you, one which you cannot ignore.
Suffering in silence won't work.
Getting angry and having disputes won't work either.
Both of those approaches will only make things worse.
You really need to get some professional help before your marriage starts to slip away.
Obviously you are concerned and have made a preliminary outreach by contact JustAnswer.
I strongly urge you to find either a marriage and family counselor or a certified sex therapist, who is usually a mental health therapist with additional training and certification.
For the former, go to www.psychologytoday.com, enter state and city, and search, narrowing it down to family problems or sex therapists.
For sex therapists (my recommendation) go to:
AASECT - Member Directory
click on your state and search for someone nearby.
On both sites you should try to find someone who seems experienced and empathetic.
The people at AASECT will be consistently of a high caliber. The ones at psychologytoday may not be well versed in dealing with sexual problems, but some can be masterful therapists.
Once again, I urge you to talk to your wife about getting professional help, as you will suffer if you do not.
Let me recommend one book for you as well:
I shall keep you in my prayers.
Elliott, MAE, LPCC, NCC, CCMHC