Feeling worthless

At the beginning of this year I noticed that some of the negative aspects of my personality were becoming more pronounced. It has started wearing on the relationships I have with my family, friends and partner. Over the past year I have alienated my friends, spending as little time as possible with them because I feel inept in social situations, often feeling anxious when around some of my old friends and it is very difficult to get the energy to go out anymore. I am very irritable with my family and partner. I feel down and weepy very often, usually resulting in crying spells. When doing things that used to make me happy I often find that i don't have enough desire to do them, or that they aren't as enjoyable. In regard to my appetite I either eat constantly or spend entire days not eating. My sleeping patterns are very irregular. I find it hard to sleep at any time before 5 am and I usually oversleep when I need to wake up in the early hours. Recently I have been suffering frequent suicidal thoughts and thoughts of harming myself. I have little to no self esteem and often feel like a burden to others and that I am worthless. I am very pessimistic about future events. Also for the past few weeks I have feel feeling very physically ill, usually suffering from backache, headache and aches in my joints. I have suffered from a few panic attacks and have experienced palpitations and dizziness. Any ideas?