My daughter just bought her first house. She has a sulfur smell coming from both sides of the kitchen sink. After using a drain build up removal agent, then bleach, then vinegar, then taking the P trap apart & cleaning it by hand, the sink still not only smells like sewer, but the sinks usually gurgles up when you drain the sink water. I've attempted to enclose pictures of the set up under the sink. Would this be a plumbing set up problem, a vent problem, or what? Any help is appreciated. Thanks!