Hi Scooby,
very sorry for your brother... and you can be sure that your flareup is related to that severe stress. Antireflux drugs can provoke twitches excatly because of depleting on Ca-Mg, so your doctor is right.
it is also common for our twitches to upset us when we going to bed.
As for natural remedies, it is funny but a cup of good tea with cream and sugar (in an old English way) helps alot to get sleepy and sleep well. tested that many times on myself and on other people

)) A walk in about three hours before going to bed also helps. There are some strong normotonic herbal meds (those to normalise mood and help with sleep disorders), based on valeriana root (I personally use a drug made of valeriana root, thorn and leonuria, it is practically strong sedative called sedaphitone, but I do not know if you have that in your country, it is rather common in an Eastern Europe), also st johns wort is strong herbal sedative but it can be dangerous and should be used with great care.
I would also like to say that severe ilness of a close family member needs a special attention and care too. Are you attending any special programs for relatives suffering those circumstances? I was translating quite a lot of materials once im my career regarding those issues and programs, and I know that such programs might exist and should be also helpful.
Another note I would like to made is that zoloft is not the only SSRI and not the only antianxiety med, so you also may refer back to a doctor asking for another treatment program.
with sympaties,
Yulia