I’m a licensed counselor and one thing I would highly suggest is a thorough CBC panel by your PCP.
After your PCP can rule-out any physical issues and treat those, I would also begin working with a therapist. From what you have posted, it sounds as if you may have Bi-Polar II, which is a milder form of the two types - the types are further divided, and based upon the information you have provided, I would guess you are NOS, at this point.
One thing that may help you understand the bio-chemical aspect of BPD is that it’s essentially a lack of a salt in the brain - it is mined and given in the shape of a pill called lithium - it’s an “older” treatment, but many psychiatrists still like it, as do their patients. There are many drugs used to help with BPD as well as depression - and if you have BPD, there really is not any method other than medication and therapy that has been proven to help, unfortunately.
The pattern of many with BPD is that during their depression phase, they do take the medication and attend therapy, but during the upswing or “manic phase” they tend to believe they no longer need the medication - or sleep - or sometimes even food! It manifests different in different people.
Now, I am not saying you are BPD II - I am only saying that based upon what you have shared on this BB, that is what it sounds like. Your PCP can recommend a psychiatrist and therapist that can help make a correct and suitable diagnosis and help you get on the past to healing.
Remember - even if you are diagnosed with BPD II or anything else for that matter, it’s merely a name to explain the symptoms you have - it doesn’t define who you are as a person - you would still be you - a horse lover/rider/trainer that is dealing with a physical issue in the brain. 
If you would like any help locating a therapist and/or psychiatrist, or would just like to chat, feel free to PM me. 
It will get better - and remember - all of us are crazy, just some of us get caught! :lol: