BIG BLACK spots with a hole in the center

[sherzumr]

Hello!
I bought a 'crassula campfire' along with two other succulents online (ordered them on 16th, got them on 28th), simply because they aren't available in the local nurseries.
They were light green in colour and looked perfect.
The next day evening, i notice that the edges of the leaves had a red tinge.
on 30th (yesterday) morning-before i left home (about 6am), they seemed fine..or maybe they looked ok to my untrained eyes. At about 7pm..i notice that the leaves have drooped and there are BIG black wet spots - with holes. Like somebody shot em with a tiny gun. I bought 2 other succulents with it (flapjack,jade plant) and they seem fine till now..so i guess its not the work of some insect..assuming they wouldve attacked the other plants as well (I HOPE not!!)
PLEASE help..i feel horrible. Is it over watering? I did not change it into a different pot yet, thinking i'll wait a day or two till they get used to the climate here...for some reason, i felt the change in climate quickly followed by a change in soil (repotting) might be stressful to the plant. what did i do wrong??
These are the pictures...on 29th and 30th.

[greenknight]

The black spots are disease, remove the infected leaves and isolate the plant.

The red is normal, why it's called "Campfire".

[sherzumr]

Thank you greenknight.
well, i removed all except one seemingly normal leaf. Next day morning, that rotted too.

Today the base of the plant was black with white patches.
the new leaves at the tip look shriveled (the earlier leaves look shriveled too)
No pics as my laptops dead.
help

[esp_imaging]

Where are you, what is your climate?
Also, the compost doesn't look great, what is the plant potted in? Have you been watering it at all?

[sherzumr]

Hi..
So sorry for the late reply..(dead laptop, shifting to a new house and exam)
I'm from the state of Kerala, also known as the "land of coconuts" or God's own country (lol),India. Tropical climate..and if Google is to be believed, we have a hardiness zone 10-11. It's a nice climate..for people - not sure abt succulents though..rains like crazy for about 5-6months..rich fertile soil in most regions..rice,banana,tropical fruits Nd vegetables are cultivated here.. Eastern region has sandy soil due to the coast and is usually hot and humid.
I left the plant in the pot it came in (came frm another part of India..completely different climate)..the soil seemed light pink,clayey,tight. By day two, it showed the following changes. I changed soil immediately. I read that succulents grow well in a sand+perlite mixture..these still hasn't reached me after ordering them online
In the picture u see, it's rainwater washed sand with Coco peat (since fast draining substrate is required and I couldn't find anything else)..
I will change the soil.
Ours is a wet/humid climate..I only watered it once..
The plant died a day after it arrived..wen I removed it..the root was rotten and there were tiny silver white mite-like things running around it..this soil and the one where i've planted the Jade plant. The Jade plants fine..but it has neither died nor grown..but looks good.
The soil here is usually teeming with tiny bugs..but the crops grow fine..(people here believe that fertile/organic soil will have living creatures that keep it that way)..but I'm not sure about these..all the other succulents are fine. Is there anyway to get rid of these? I heard of some cinnamon mixture..how efficient are those?
I'm going to water them with tea water next time..that's fine right?
Anybody else living in anti-succulent regions have any tips and tricks for me?