Firstly my heart absolutely goes out to you. My partner, aged 62, was diagnosed May 2013, a very aggressive disease which didnt really respond to any treatment for any length of time and he died sixteen months after diagnosis so I appreciate the situation you are in and the emotional distress it is causing you.
Obviously no one can give any guarantees regarding your husband, this disease is so unpredictable and, along with the treatments, plays havoc with all sorts of bodily functions, hence the erratic blood readings you mention. Your husband is likely to be fatigued with the spread of the disease and barrage of treatments not to mention the stress of having a life limiting illness. Have you and your husband been referred to a local palliative care service, who are experts in supporting patients and families through this most difficult of times? I wish my partner had been referred much earlier as this service was the one thing which took some of the pressure and stress off me as carer and with hindsight , it's something I always suggest to people. We have a number of threads on the forum asking a similar question to yours, eg., is this the end and it might be worth searching the forum for them. The other thing is preparedness, hard as it is, having arrangements in place over end of life, where ? access to controlling pain, your partner being able to have some choice if you are able to broach these things with him, you may already have done so.
We have some men on the forum whose situation seems critical, but then they rally, often those with treatable issues like infection or following a blood transfusion. Some men feel better on steroids which help with fatigue. Have you talked over your concerns with your medical team as to what further treatment is available or come to a decision when it would be better not to subject your husband to further treatment bearing in mind quality versus length of life. Are there little goals you husband want to achieve, eg being reasonably well for Christmas ?
As this phase progresses, the world often seems to shrink and realistic plans which make your husbands life worth living are important. Do you have support for yourself, the PCUK Helpline is excellent as are Macmillan. There are a number of men on the site who have had experience of Enzalutamide, again with varying results depending if their particular disease is responsive or not, again, the pros and cons need to be clearly outlined by your husbands medics.
I send you my sincere best wishes, it is ghastly place to be in. You will get huge support from this forum, people just offering their best wishes as well as more specific answers.