Suggest Treatment For Suicidal Thoughts While Having Depression

Question: Hi, i have been suffering with depression for quite a while but recently mum mum past away and i have been suffering with anxiety. My dr wants to change my depression tablets to cover the anxiety but i feel that my depression untill now has been under control. I feel stuck in a rut. I cant eat (lost a stone in a month) cant sleep (averaging 2-3 hrs a night), have lost interest in everything even my job which is usually love, i have no self esteem or confidence. Because how tired i am ive been taking ketones but about 8-12 a day when i know you can only have 2, im drinking lots of caffeine drinks and coffee, i feel shakey and awful if i dont have it, and on top of the world when ive had it. I fainted the other night due to feeling so rough when it wore off. I keep having palpatations, feeling dizzy and vomiting. If i dont have the tablets or drinks i get shakey as well. The last few days i have had great relief in hurting myself, ive never done it before but feels as though the only way i can show how much im hurting inside. I dont mean cutting or anything but making myself bruise and biting my skin. The instant i do it i feel relaxed. I know its wrong. Last night i confided in someone for the first time in my life and i felt so embarassed and worried about what he would think, he said he would help me through this but i feel a burden. Today for the first time ive had a feeling of suicide. I know my gp said by coming off my tablets to start my new ones i would have a period of not having much antidepressant in my system so may be it is that i dont know. I know i need help but i dont know where to turn. I cant talk to people, i clam up, the only way i can talk is by message like i did with my friend and why i am messaging on this site. Ive tried counselling and phone lines before and i cant benefit from it. I was sat with my legs dangling over a cliff top wanting go but bottled it. I cant stand feeling so low and empty anymore. Please help me.