smallest BLE module for telemetry

I would suggest you look towards Taiyo Yuden's Nordic Semiconductor nRF modules. They are a microcontroller and BLE radio in one - common to find in wearable/medical.

e.g. www.nordicsemi.com/.../taiyo-yudens-new-module-employs-nordics-nrf52805-soc

Another candidate might be an Infineon CY8C4247LQI-BL483. It is an ARM Cortex M0 with BLE, optimized for low power, in packages as small as 3.52mm x 3.91mm.

Look at https://www.onsemi.com/products/wireless-connectivity/bluetooth-low-energy/rsl10%20sip which is 8x6mm SIP containing chip, antenna, crystals and required passives. Dialog offers some small module also but they most probably will not fit 10x10mm. For example, shabaz wrote blog about DA14531:  Easy, Cost-Effective Bluetooth LE (BLE) with Dialog DA14531MOD 

Second this suggestion. Element14 also roadtested these fantastically small modules.

Here's my review: community.element14.com/.../taiyo_yuden_bluetoot_1

NRF5340 can be considered too. it's an all in one - BLE, Thread + Zigbee
I think it's a good choice for medical device as it's dual core. there are two separate processor for network and application.
It has more GPIOs [48], huge flash and RAM. And it also supports USB protocol. So, lots of processing power with tools.
it's small [7x7 mm maybe] and less power hungry. However, straightforward PCB integration can be a challenge. In that case modules could be a solution.
I know Gough Lui posted an excellent road-test review on the development kit for this SOC.

The problem is that 7x7mm is size of the chip but you need antenna, crystal, sometime external flash also. With 7x7 mm chip you are mostly impossible to do this. For this reason, makers of tiny modules use much smaller chips even they are not the highest tech avalaible.

Yes, it has been a long time since my review of the Nordic Semicionductor nRF5340 Audio DK which is a pretty nice chip.

However, I didn't mention it because the poster was asking about modules rather than SoCs - most of the time, modules can be preferred in designs for ease of integration and certification (as they may already carry global radiotelecommunications certifications meaning fewer tests compared to designing a board with a raw SoC). Usually they will include an antenna as part of the module as well, but not always.

- Gough