You may be experiencing an allergic reaction where the filler was injected. A suggestion would be to take an antihistamine and schedule a follow up with your injector.
Consider possible foods that may be causing this reaction.
Hope this helps.
Appears as allergic reaction to the filler. BTW "which filler was it?" & "how/who injected it?" Best to return to the injecting doctor for care. I would start on steroids by mouth and injection. warm compresses, and antibiotics for a week. If this does not resolve than you would need a skin biopsy of area injected to determine if there is an issue. Sorry.
Thank you for your pictures. This is unusual. This may be a slight allergic reaction versus mild cellulitis/infection of your cheek. Any immediate evaluation by your plastic surgeon.