Thank you for your query at DoctorSpring.com
I understand your concern.
No, you definitely do not need any further testing for STDs. at 8 weeks the results are conclusive and also Syphilis does not present with the symptoms you are having. They are likely to be due to the allergies as your doctor mentioned. So, kindly do not worry.
Feel free to discuss further,
The picture you shared is typical of ringworm and is not any STD.
She can apply Clotrimazole ointment on the lesion as well as take Tab. Levocetirizine 5 mg once daily at bedtime till it resolves.