Scalp damage by chemical treatment.

In younger around 17 years did chemical hair straightening by a unprofessional which resulted in immediate loss of hair after 15 minutes in form of furr balls or lumps if you can call it,dont know medical term for that,after that felt rough and itchy skin since now even after 10 years or so,now hair are good due to some orgnic oil treatment but still they are not what they used to be so thick and full also now itchy and sometimes dandruff,because of lack of knowledge and limited facilities couldn't get proper medical advice for that time ,so question is: Can something be done after so many years of damage probably chemical burned treated by straightening by velocity lotion or something like that and what will be the cost ? Thanks in advance.