Hyaluronic acid fillers can be used by experienced physicians for the tear trough area. It is difficult to identify in your photo, but discoloration may be due to lifting a previously discolored area and making it more prominent appearing. There can also be an effect seen where the area treated takes on a deeper or bluish tint as well. It is important that you notify your physicians and have them evaluate you further. There maybe some treatments they can do to help alleviate this coloration as well.
Restylane and other hyaluronic acid fillers can be a great option for improving tear troughs. However, often the injections are not carried out well. Superficial injection can make the product visible with swelling and lumps. Too much filler can cause swelling of the lids. One consideration in patients with dark circles is that filler may make the darkness more apparent as it is lifted from the hallows. In patients with darker skin, it is often best to combine filler with topicals, peels, or laser treatments to reduce the hyperpigmentation of the tear trough. It is difficult to determine from the picture what exactly is going on. It could be pigmentation from bruising ore pre-existing pigmentation that was lifted up or swelling from fillers. I recommend seeing an expert injector in your area to be evaluated. It pays to see an expert when considering fillers especially around the eyes.