6 months post tear trough filler and red bump developed. Could the filler got infected? (photo)

While an infection after dermal fillers is not impossible, it is quite rare. You may be experiencing a delayed hypersensitivity reaction, which can happen weeks to several months after the injection. Often times it presents as swelling or lumps in the area of injection and can also be associated with pain and redness. Occasionally this will calm down on its own with gentle massage, or it may require injection of a steroid or Hyaluronidase to break down the remaining filler. I would recommend being evaluated in person by someone who is very experienced with filler injection and its associated complications. Best of luck to you!

It's a little difficult to tell from the photographs but it looks like you may have a cherry angioma forming after a trauma from the needle. I would recommend to see your treating physician who should reevaluate you and offer a treatment. if this indeed looks like a cherry angioma a laser should do very well on this. At the same time the blue hue that you have in the lower eyelid is What's called the Tyndall effect and this is exactly the reason why I don't recommend having fillers put in the tear troughs but instead use the patient's own fat which produces natural and long-lasting results. Good luck from New York City

Thank you for your question.  This could be due to a delayed onset infection though that is rare.  I would certainly have it evaluated by a dermatologist.  I would also consider your eyelash extensions as a possible cause.  Best to have it evaluated ASAP.