CheckedChanged Event in a Gridview checkbox to update hidden labels - asp.net

Question

I have a gridview where the first column are check boxes, the next column is ID's. I have hidden labels on the page that need to get the current ID for any check boxes checked. The labels are specific, hlbl_pain1, hlbl_pain2, hlbl_pain3. It doenst matter which label gets which ID I just need each of the 3 hidden labels to be populated with ID's. Right now on CheckedChanged the 3 labels all update with the same value. I'm having issues looping. This is in VB.
Here's my grid:
<asp:GridView ID="gv_pain" runat="server" AutoGenerateColumns="False" BackColor="White" BorderColor="#999999" BorderStyle="Solid" BorderWidth="1px" CellPadding="3" DataSourceID="ds_grid_pain" ForeColor="Black" GridLines="Vertical" style="text-align: left; font-size: x-small; ">
<AlternatingRowStyle BackColor="#CCCCCC" />
<Columns>
<asp:TemplateField HeaderText="Select">
<ItemTemplate>
<asp:CheckBox ID="CheckBoxPain" runat="server" AutoPostBack="True" Checked="false" OnCheckedChanged="CheckBoxPain_CheckedChanged" />
<asp:HiddenField ID="HiddenField1" runat="server" Value='<%#Eval("DrugID")%>' />
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="DrugID" InsertVisible="False" SortExpression="DrugID">
<EditItemTemplate>
<asp:Label ID="Label1" runat="server" Text='<%# Eval("DrugID") %>'></asp:Label>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="lbl_DrugID" runat="server" Text='<%# Bind("DrugID") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField DataField="NickName" HeaderText="NickName" SortExpression="NickName" ItemStyle-Width="150px">
<ItemStyle Wrap="False" />
</asp:BoundField>
<asp:BoundField DataField="DrugName" HeaderText="DrugName" SortExpression="DrugName" ItemStyle-Width="500px">
<ItemStyle Wrap="False" />
</asp:BoundField>
<asp:BoundField DataField="Quan1" HeaderText="Quan1" SortExpression="Quan1">
<ItemStyle Wrap="False" />
</asp:BoundField>
<asp:BoundField DataField="Quan2" HeaderText="Quan2" SortExpression="Quan2">
<ItemStyle Wrap="False" />
</asp:BoundField>
</Columns>
<FooterStyle BackColor="#CCCCCC" />
<HeaderStyle BackColor="Black" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="#999999" ForeColor="Black" HorizontalAlign="Center" />
<SelectedRowStyle BackColor="#000099" Font-Bold="True" ForeColor="White" />
<SortedAscendingCellStyle BackColor="#F1F1F1" />
<SortedAscendingHeaderStyle BackColor="#808080" />
<SortedDescendingCellStyle BackColor="#CAC9C9" />
<SortedDescendingHeaderStyle BackColor="#383838" />
</asp:GridView>
Here are my labels:
<asp:Label ID="hlbl_pain1" runat="server" Visible="true"></asp:Label>
<asp:Label ID="hlbl_pain2" runat="server" Visible="true"></asp:Label>
<asp:Label ID="hlbl_pain3" runat="server" Visible="true"></asp:Label>
Here's what I'm trying to do in my CheckedChanged in the codebehind:
Protected Sub CheckBoxPain_CheckedChanged(sender As Object, e As System.EventArgs)
Dim row As GridViewRow
For Each row In gv_pain.Rows
Dim cbPain As CheckBox = row.FindControl("CheckBoxPain")
If cbPain.Checked = True Then
Dim lblDrugID As Label = row.FindControl("lbl_DrugID")
hlbl_pain1.Text = lblDrugID.text
End If
Dim cbPain1 As CheckBox = row.FindControl("CheckBoxPain")
If cbPain1.Checked = True Then
Dim lblDrugID As Label = row.FindControl("lbl_DrugID")
hlbl_pain2.Text = lblDrugID.text
End If
Dim cbPain2 As CheckBox = row.FindControl("CheckBoxPain")
If cbPain2.Checked = True Then
Dim lblDrugID As Label = row.FindControl("lbl_DrugID")
hlbl_pain3.Text = lblDrugID.text
End If
Next
End Sub