hello and welcome to HCM forum Argarcia1986,
according to the dental history provided by you i would like to inform you that you need not worry , the red bump might be painless therefore your son did not complain of any pain, and as your son is 17 months old, his milk teeth might be erupting.
whenever a tooth erupts ,surrounding area is sore and inflamed, therefore its red and sometimes a child feels pain, but it may be painless in some cases as well.
i would recommend you to take your son to a dentist
to check for any infection with respect to the erupting tooth.
i hope i answered your query,
i wish you you good health,