Hello & welcome
As you said that wisdom tooth got extracted before 10 years and there was no problem, than we can rule out this point, there may be two reasons of:
firstly and mainly there may be some proximal caries in your present last molar causing all these symptoms.
secondly there may be some gingival inflammation
causing peridontal pockets resulting in pain & sensitivity.
As you are pregnant,3-6 months of pregnancy
are safe for any dental treatment so please visit to your dentist
and go for a proper clinical checkup.
Thanks & take care.