Reduced Smoking, Have Persistent Headache, Tightness In Chest, Breathing Difficulty. Cause?

I am a 35 year old female, light smoker (in the process of quitting). In the past 2 weeks I have reduced from 6-7 cigarettes down to 1 per day. I thought i would feeling a lot more better however i now feel even more unhealthy. It Started with a persistent headache on the back of my head, lower left which lasted 1 week. I feel a tightness in my chest , even more short of breath than before. Last night I started to experience severe lower back ache, I find it difficult to find a comfortable sitting or sleeping position. The back ache seems to have aggregated my shortness of breath even more, especially if I inhale deeply I can feel a sharp pressure in the centre of my rib cage. The headache seems to have subsided but I would like to know what is causing my lower back pain and tightness in chest area which is making it uncomfortable to breath. I occasionally get some dizzy spells which lasts for a few seconds.