Best treatment for a fresh nearly 3 weeks old keloid surgical scar on neck. I have starting yesterday to use the silicon gel called dermatix 15g.?

Excess scar. Unlikely a keloid (defined as a scar that grows outside the edges of the scar) and more likely a hypertrophic scar (excess reaction). Silicone gel sheeting is used to sooth and quiet the early scar. If symptomatic (like itching, stinging, etc) some will be treated by diluted kenalog (triamcinolone) (steroid) injections into the scar itself to attempt to slow or stop the scarring excesses. See your dr to confer.
Steroid injection. Early keloid scars can be managed with routine injections of kenalog (triamcinolone) (a steroid anti-inflammatory), silicone sheeting, or silicone gels. Spf sunscreens and sun precautions should be taken with all scars. Microderm, laser resurfacing, and surgical scar revision can all be considered in the long term. Hope this helps!
? You don't have a keloid- its not possible to have one three wks after surgery. Your choice is good prophylaxis for keloid. Mederma and related drugs plus massage also good options. If there's a mass you need to see your surgeon adap.
Not likely a keloid. This is not likely a keloid but rather the normal phase of wound healing we call the inflammatory phase where the scar turns red and swells up. Massage of the scar and the topical silicone you mentioned can help. Protect it from the sun. You may see slow improvement for as long as a year.
Continue. I would continue with the dermatix and consider steroid injections under the guidance of your surgeon.