Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain it seems that you have had an allergic reaction
to the chemicals present in hair dye leading to swelling, tightness and pain.
Pain behind the ear can be due to swollen lymph nodes
secondary to inflammation due to allergic reaction.
As the swelling has subsided now you need not to worry as gradually the weakness will also subside that can be seen commonly BBC after allergic reactions..
In case if there is some discomfort still present you can take anti allergic like Benadryl
and do cool compresses over the scalp
Avoid using hairdyes with similar composition in future as it might lead to further more severe allergic reaction..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.