My wife has suffered from similar feelings for the past 4-5 years, and after therapists and anti-depressants did very little to help after initial success, we stumbled across accounts of these and her other symptoms (weight gain, excessive tiredness, IBS, lack of concentration, etc.) from people using the Mirena coil for contraception, as she was. She had it removed, and within a week I had my wife back. Any hormone-based contraceptives can do this, we've found, but not a single person in the medical profession ever even asked about contraception in all that time. Based on our (admittedly biased) trawling of the net, the mirena coil specifically has a very high incidence of it, and it's comparatively more severe too.
Another ‘comment of the year’ from Reddit: