Hello! Please remember that my response is for information only, we are not establishing a therapeutic relationship.
I can't give you a definitive diagnosis over the internet, but given that they already think that you have hypomania and from what you are describing, it could possibly be what they call "Ultra-Ultra rapid cycling." The shifts in mood are supposed to occur over a 24-48 hour period. Another term that is used is "Ultradian Bipolar."
The cause of the rapid cycling is not known, although there are three theories:
1. Kindling (sensitization): This theory states that a person was exposed to or anticipated life events (that range from mild to traumatic) and that over time the person gets triggered by milder and milder forms of stress then can have episodes without any triggers at all.
2. Biological Rhythm Disturbance: This theory states that biological rhythms are disturbed and although they don't cause the rapid cycling they contribute to the length and seriousness of it.
3. Hypothyroidism: This theory states that people have inadequate levels of thyroid hormone in their blood. They also assert that even if the blood level is normal that treatment with the hormone can help.
Whether or not these theories are correct, it is well established that finding the right treatment for rapid cycling is difficult. So, I'd like to encourage you to be patient and keep trying. Here's an article that you could show to your doctor and ask him/her about: http://www.medscape.org/viewarticle/512156_4
Please feel free to follow up with me.
I have no personal experience with supplementing lithium with folic acid, so you should check with your doctor or Pharmacist. However, according to things I found on the internet --it appears to be beneficial.
Here's one article supporting the use of folic acid with lithium: