4 weeks PO TT, incision opened up and leaking. What is going on? (photos)

My incision opened up around 3 weeks and it has not fully healed. I thought it was closed back up but tonight it popped back open and leaked tons of yellow, oily fluid with a little bit of blood. What is going on? I went to my doctor when I first noticed it opened up, and they told me to do local wound care and that it was probably a stitch spitting out. But it hasn’t seemed to fully heal. The size of the opening is about 1-1.5 cm. I don’t notice any pus, smell, or hotness.