There are multiple glands that play a role when it comes our dogs. There are cases where one or more can get impacted, leak, or traumatized resulting in swelling of the tongue, swelling under the jaw, smacking of the lips, excessive durling, difficulty swallowing or chewing and abdominal respiration.
Any impaction is painful to a dog and medical care and diagnosis needs to be seeked immediately.
Normally aspirating or draining does not solve the root cause of the issue. Unfortunately the surgery required is not common practice thus we suggest you call around for a clinic that has experience.
Removing a salivary gland may be required if that will solve the issue however sometimes it is just unplugging the gland and making the exit hole larger for proper drainage.