I am sorry to hear your not feeling so well.
What you are describing sounds a lot like vertigo..
Vertigo comes in two forms, it could be a spinning sensation or a motion sensation. Subjective meaning you feel the motion or objective meaning your surroundings are spinning or moving. You can feel any sensation in the range of a swaying to the side, falling backwards, tilting, constant motion, a dropping sensation or sinking to the ground feeling, a sensation as if you are on an elevator, being on a boat sea sick sensation, as well as a violent spinning as if you were on a spinning carnival ride!!
You may also feel like your head is heavy, woozy and you may also experience fatigue as well as headaches.. That being said.. There are several illness that can cause vertigo, which means vertigo is not a illness in it's self, it's a secondary symptom to an illness. First common illness is inner ear disorders, Migraine's can cause vertigo, anemia, central nervous system disorders, thyroid problems, blood pressure problems as well as neurological and cardio disorders and allergies among a few others. Vertigo can appear suddenly, you mentioned you started to feel this way out of the blue.. So you see there are many things that need to be ruled out.
often times there is no true explanations for why one is suffering from vertigo, and may be a secondary symptom to anxiety or better known as Physiological vertigo..
I am not sure if what your feeling is as described above.. If so it's safe to say you are experiencing vertigo.
I am a vertigo suffer as well and know the true impact this can cause on your life, please keep in mind that vertigo can be the cause of anxiety as well as panic disorder. I hope you find this information helpful and any thoughts or questions please feel free to ask! Boxerlover