I am sorry to hear you are worried about Jingles. My name is Rebecca. I am a veterinarian and will do my best to help.
Is she still eating, and drinking?
Good that her stools are not loose, and the skin pinch test looks good. If you check her gums, are they pink in color?
You can give famotidine (Pepcid AC), but you will have to cut the pills very small. If she is 6 weeks, she is probably between 1 and 2 pounds? So you can give .5 to 1 mg of Pepcid twice daily, but the over the counter pills are 10 mg, so you will have to cut them very small, give a piece that is 1/10th to 1/20th of a pill.
If she is eating, probitoics may help. I like ones made especially for cats, like Fortiflora or Proviable. Probiotics are beneficial bacteria supplements.
Let me know how her gums look, and what else I can help with or answer. Rebecca