Welcome to SOF, the problem you have is always point to the first, when you execute a method remember that when you use the object this
you refer to the current object based on that defición it is possible to do this:
$(function(){
$('.control-colapse').click(function(){
$(this).parent().find('.collapse').toggle();
});
})
I'll give you an example so you can adapt it to your code.
$(function(){
$('.control-colapse').click(function(){
$(this).parent().find('.collapse').toggle();
});
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<div class="main-group">
<div class="hgroup">
<h4>Neumología</h4>
<!--<p>Dr. Avis Stankovic</p> -->
</div>
<button type="button" class="btn btn-xs btn-primary control-colapse" data-toggle="collapse" data-target="#demo">
<span class="glyphicon glyphicon-collapse-down"></span> Open
</button>
<div id="demo" class="collapse">
Lorem ipsum dolor sit amet, consectetur adipisicing elit,
sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
</div>
</div>
<div class="main-group">
<div class="hgroup">
<h4>DIV 1</h4>
<!--<p>Dr. Avis Stankovic</p> -->
</div>
<button type="button" class="btn btn-xs btn-primary control-colapse" data-toggle="collapse" data-target="#demo">
<span class="glyphicon glyphicon-collapse-down"></span> Open
</button>
<div id="demo" class="collapse">
DIV 1 Lorem ipsum dolor sit amet, consectetur adipisicing elit,
sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
</div>
</div>
<div class="main-group">
<div class="hgroup">
<h4>DIV 2</h4>
<!--<p>Dr. Avis Stankovic</p> -->
</div>
<button type="button" class="btn btn-xs btn-primary control-colapse" data-toggle="collapse" data-target="#demo">
<span class="glyphicon glyphicon-collapse-down"></span> Open
</button>
<div id="demo" class="collapse">
DIV 2 Lorem ipsum dolor sit amet, consectetur adipisicing elit,
sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
</div>
</div>
<div class="main-group">
<div class="hgroup">
<h4>DIV 3</h4>
<!--<p>Dr. Avis Stankovic</p> -->
</div>
<button type="button" class="btn btn-xs btn-primary control-colapse" data-toggle="collapse" data-target="#demo">
<span class="glyphicon glyphicon-collapse-down"></span> Open
</button>
<div id="demo" class="collapse">
DIV 3 Lorem ipsum dolor sit amet, consectetur adipisicing elit,
sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
</div>
</div>
Good luck!