Thank you for your very helpful and understandable advice.
She is on both of those medicines for it, however if she misses a single dose, she is right back to having a severe reaction again. We have brought her to a larger hospital and they took blood samples again. Her feet looked fine for the appointment, unfortunately. Now that she is home, she missed a dose and it is back. The swelling is down but she has the purple spots and severe pain. We will get her back in and bring your advice with us.
Does this serum sickness go away at some point?
Congestion can lead to the blockage of the veins which turns bluish or purple in color and can lead to palpable purpura. Such lesion initially starts with Petechiae, and then due to confluence of these petechiae will lead to larger lesions known as purpura which has reddish to purplish discoloration. The condition in which such lesion can be seen is thrombocytopenia and she needs to get her platelet counts. If low then she may need platelet transfusion.
She needs to be managed by anti-histaminic and as well as steroids which take care of the allergic symptoms and joint pain. Avoid future exposure to penicillins and cephalosporins. I suggest you to consult your doctor. Take care and regards.