I am sorry to read you are not feeling well. Feeling down can be a side effect of quitting. Exercise, eating healthy, doing pleasant activities and spending time with loved ones can help. As you are still smoking it is hard to say how long the symptoms will last. Generally only a few weeks after you quit are symptoms at their worst.
Having slips during this time is also common - and some consider it part of the learning process. Do you feel you are ready to stop the 2-3 cigarettes a day? You might want to talk to a doctor about medication that can help you - NRTs and Champix have shown to be effective in helping people to quit. Using NRTS might also lesson the side effects you are experiencing.
I am currently quitting too and I have just made it to day 6 (no slips) and I am still feeling a bit cloudy in the thought department. I did feel a bit down around day 2 and to get my mind off things I began to keep myself occupied with as much physical activity as I could. Working out, Walking, Cleaning like a mad woman, Gave my truck a tuneup (when it didn't need it) - Just anything to keep my hands and my mind busy. I found this also helped clear my head a bit and I felt better just because I accomplished something other than smoking that day. It is really hard to make it through the first week - I haven't had a lot of withdraw symptoms so my attempt is a bit easier than most, But the WANT for a cigarette is there. Its just finding a way to not give into that want thats the hardest.
As for when you'll start feeling better - Everyone has said the first 7 smoke free days are the hardest, The Second week is still gonna be rough but not as bad vs. week one. But from what everyone has told me, After that its easier. But there is always gonna be that looming temptation to smoke - you just gotta keep saying no.