Withdrawal even after months: How can I concentrate on my work?

I have a huge withdrawal problem. I'm not a smoker, but only took nicotine. I can withstand my body constantly asking for nicotine but I can't get my body to concentrate on my work again without nicotine, even after 2.5 months withdrawal. So I had a relapse 12 days ago. I could immediately concentrate and work.

But it was a short relapse, because the fact that I was able to concentrate was the only good thing. I fucking hate the side effects (cold hands, higher heart rate) and so immediately stopped taking nicotine and so I can't work.

When I wake up, I want to work and I am optimistic. But I forget everything, I am always distracted. It's so difficult for me to focus on my work. I can't even do housework, I feel like a very stupid or demented person now.

I'm diagnosed with ADHS unfortunately, but I didn't take medication because I'm afraid that it has similar side effects as nicotine. I don't want to have a higher heart rate while sitting and working.

I just want to be a normal person with no drug or medication addiction.